I wouldn't choose any of the 3, but I run a pretty tight ship when it comes to my operating system (no haxies, appearance mods, etc.) so it's as stable as stable can be without the need for 3rd-party maintenance.
I do repair permissions after installing new software, occasionally boot from the OS X install CD and check my hard drive health, and let my computer stay awake at night once or twice a month so the cron scripts can run.
This maintenance routine has kept my systems running 24/7 with uptimes in the months without any stability or operating system problems whatsoever.
The days of constant maintenance under OS 9 are gone with OS X.
I like Cocktail more than the other two.